Goalkeepers prone to ‘gambler’s fallacy’ but penalty takers fail to exploit it

31 July 2014

After a string of penalties aimed in the same direction, goalkeepers are
more likely to dive in the opposite direction on the next penalty but kickers
fail to exploit this pattern, finds new UCL research.

The study, published in Current
Biology, shows that penalty shoot-outs in international tournaments
resemble a psychological game. The researchers studied penalty shoot-out videos
from all World Cup and Euro finals tournaments between 1976 and 2012.

They found that each team of kickers produced more or less random
sequences of kicks to the left or the right of the goal. Goalkeepers’ dives to
the left or the right were not related to the direction of the kick, suggesting
that goalkeepers at this elite level make their decisions in advance, rather
than reacting to each kick. However, goalkeepers’
decisions were non-random in one crucial respect: when the kickers repeatedly
kicked in the same direction on consecutive penalties, goalkeepers became more
likely to dive in the opposite direction on the next penalty. After three consecutive shots in one direction, goalkeepers dive in the
opposite direction for the next penalty around 69% of the time.

The goalkeepers
therefore display what has been called the ‘gambler’s fallacy’ – like a person
who believes that after coin flips produce a run of ‘heads’, the next flip is
bound to produce ‘tails’.

“Complete randomness is generally the best strategy in competitive games”
says lead author Erman Misirlisoy of the UCL Institute of Cognitive
Neuroscience. “Because the goalkeeper
displays the gambler’s fallacy, kickers could predict which way the goalkeeper
is likely to dive on the next kick. That
would obviously give the kicker an advantage – they would simply aim for the
opposite side of the goal. Surprisingly,
though, we found that kickers failed to exploit this advantage”.

This demonstrates a crucial link between the habenula and motivated behaviour, which may be the result of dopamine suppression.

Professor Patrick Haggard

“Often you can only win in elite sport by exploiting tiny weaknesses in
your opponent’s strategy”, explains senior author Professor Patrick Haggard.
“We can only speculate on why goalkeepers can get away with non-randomness,
without the kickers exploiting it. One
possibility is that penalty shoot-outs are relatively rare. But there is a more psychologically
interesting possibility: shoot-outs are asymmetric, because one goalkeeper
faces several different kickers, one after the other. Kickers are under enormous pressure, focussed
on the moment of their own kick. Each
individual kicker may not pay enough attention to the sequence of preceding
kicks to predict what the goalkeeper will do next.”

Erman Misirlisoy adds: “People can learn to predict: perhaps football
coaches could study the gambler’s fallacy, and could train their penalty
kickers in preparation for the next World Cup. At the same time, goalkeepers could also learn to be less predictable”.

The research was supported by the European Research Council and UK Economic
and Social Research Council.